With the social progress and technical developments, electronic products such as a TV are decreasing in size and developing towards thin thickness in recent years, and the requirements for the performance of the electronic products become more and more critical, and thus it is demanded that the volume and the thickness of the matching electronic parts decreases continuously while the performance and consistency are continuously improved. The woofer with conventional structure generally uses a tapered paper-cone vibration diaphragm. The tapered vibration diaphragm comprises a voice coil in the center thereof, and the size of the magnetic circuit system is relatively large and thick. The disadvantage of the woofer with above structure is that the thickness thereof is too large to meet the requirements of current electronic products with thinner thickness, and thus the woofer as described above is weak in practicability.
Besides, the woofer usually has a larger caliber, that is to say, has a larger vibration diaphragm area to ensure a low-frequency sound effect. If a structure having a flat-plate shaped vibration diaphragm coupled with one voice coil is used (the voice coil should be located near the edge), the vibration diaphragm with a larger area requires a voice coil with a larger size, resulting in difficult winding and easy deformation. Further, the magnet of the existing woofer is large in size, while the thicknesses of the washer and frame is are small during thinning application, thus the magnetic circuit system is easy to be saturated, and the magnet performance is surplus, resulting in wastage and relatively high cost.
Based on the above factors, it is necessary to improve the woofer with conventional structures.